Right now, cancer is one of the most feared diseases in the world. In
the early 1990s almost 6 million new cancer cases developed and more than 4
million deaths from cancers occurred. Also more than one-fifth of all deaths
were caused by cancer and it has been predicted, by the American Cancer Society,
that about 33% of Americans will eventually develop this disease. This is a huge
disease that is killing people all over the world.
The field of cancer study is called Oncology. The government has spent
billions of dollars on research of this fatal disease. Cancer is the most
aggressive disease of a larger class known as neoplasms. Neoplasms do not fully
comply with the parts of the cell that control the growth and functions of the
cell. These cells eventually become abnormal growths and can be recognized as
not normal tissue. These traits are passed down as the cell reproduces therefore
spreading the cancer.
Neoplasms are generally classified into two groups: malignant and benign.
Malignant tumors, or abnormal tissue, grow more rapidly than benign tissue and
they invade normal tissue. Benign tissue is structured similar to normal tissue
while malignant tissue is abnormal and has an unstructured appearance. Of
greater importance, benign tissue does not metastasize, or begin to grow in
other sites, like malignant tumors do. Cancer always refers to metastasized
tumors but the term tumor is not always necessarily cancer. A tumor is any
living tissue that is distinguishable as abnormal living tissue. After a
cancer forms, it can also change from a benign to a malignant state, therefore
making the cell grow at a more rapid rate. The development of the cell starts
when it forms notable abnormalities in chromosomes and then multiplies
exceedingly. Then metastasis usually occurs and generally causes the death of
the host. There are many different cancers which form on just about all parts of
the body. In the US, skin cancer is the most common cancer, then prostate
cancers in males, and then breast cancer in women. Leukemia is clearly the
dominant cancer in children. The number one killing cancer in the world today is
lung cancer, mostly caused by the smoking of cigarettes. Some researchers have
stated that if Americans stopped smoking, lung-cancer deaths could disintegrate
within two decades. Stomach cancer is the second most fatal cancer in males and
Third is the leading cancer in women, breast cancer. The prevention of
cancer rides upon what is known about the causes. Any agent that causes cancer
is called a carcinogen. Carcinogens are generally classified into three groups-
chemical, biological, and physical. Chemicals that cause cancer have many
different molecular structures and can be just about any type of chemical. Some
substances that cause cancer are complex chemicals and gases, certain metals,
drugs, hormones, substances in molds and plants and many more. Many
nitrosamines, or simple organic oxides of nitrogen, are carcinogenic. That and
hydrocarbons are carcinogens in cigarette smoke and increase the risk of lung
cancer. Also another chemical gas, vinyl chloride, gas has been found to be an
agent of sarcoma of the blood vessels in the liver. Many drugs as well as
alkylating agents used to treat cancer are carcinogenic. Even though these
chemicals break the DNA of cancerous cells, which kills them, it also induces
cancer in normal cells. Some hormones created in humans can also cause cancer.
High levels of estrogen, which is marked as a female hormone, can increase the
chances of getting a cancer of the uterus (in women). Aflatoxin B is a substance
produced by the mold Aspergillus that causes a number of cancer, but generally
liver cancer. Many carcinogens have not been discovered but research is being
done to discover other carcinogens to keep people aware and safe. There are also
many different biological agents which cause cancers. The most common biological
agents are the oncogenic viruses that commonly bring about the formation of
neoplasms in some smaller animals. Also some of these viruses are thought to
cause human cancers, and one has even been proven to cause leukemia. These
viruses can be split into DNA viruses and RNA viruses, depending on their
genetic structure. The DNA viruses generally insert the genetic information
straight into the cells of their host. The RNA virus, contrasting, requires that
the genetic information be transcribed into DNA by an enzyme, called reverse
transcriptase, provided by the virus. All onconogenic viruses have one or more
genes that are needed for the transformation of the infected cell into the
neoplastic cell. These genes, called oncogenes, are best portrayed in the
genomes of oncogenic RNA virus. It is now seen that